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SCREENING AND FULL TESTS FOR DOWN SYNDROME IN PREGNANCY
Turkey Medicals Co-ordinator, “Now all pregnant women are offered tests in Turkey hospitals for Down syndrome. Whether these tests are performed or not has important consequences for the mother and baby.” was said
Down syndrome is the most common chromosomal disease. It is a disease that develops as a result of being one copy more than the twenty-first chromosome.This is an accidental situation. There is no cure for this condition. In people with Down syndrome, the impact can be at very different levels. Although at different levels, people with Down syndrome have learning disabilities. About 50% of them may have heart disease, decreased hearing and visual functions, organ diseases at varying rates. It is not possible to predict in advance how much children will be affected when they grow up. Most people with Down syndrome will need help in the long term.
Everyone can have a baby with Down syndrome. But the risk increases with age the older the mother, the more likely she is to give birth to a baby with Down’s. For example, a 20-year-old woman is 1/1500 A 30-year-old woman is 1/900 A 40-year-old woman is 1/100 likely to have a baby with Dawn. This is an accidental situation and it is not related to whether the parents did it or not.
Two groups of tests are performed for Down syndrome:
1- Screening Tests : These tests never give a definitive result, but they show which babies have a higher risk of developing Down syndrome. These tests do not pose any risk to the mother or baby. Screening tests are performed by ultrosonography or hormone measurements applied to the maternal blood.
2- Complete Tests : These tests give precise information, they are performed by examining the baby’s cells by taking a sample from the baby’s water, placenta, or sometimes blood. Although these tests have different rates in the literature, they are associated with a risk of miscarriage of up to 1-2-3%. Again, it will not be possible to arrive at a diagnosis from a sample taken at a rate of 1-2-3%, and the test may need to be repeated.
Due to the low risk of complete tests, it is preferable to perform a screening test first and to perform a complete test in those whose risk of Down syndrome is above 1/270.In this case, it is determined to apply the full test to an average of 5% of those who have undergone a screening test. It is possible to diagnose a Down syndrome baby with an average of 40 complete tests. Again, with these methods, Down syndrome can be diagnosed in an average of 3/4 of babies, and 1/4 of them cannot be diagnosed.
Screening Tests:
* NT ( nape transparency / thickness ) and nasal bone examination by ultrosonography at 11-13 weeks of pregnancy is the only accepted screening option for twins and triplets.
* Combined test with the addition of maternal hormone measurements to NT and/or nasal bone measurements.
* 3rd test or 4th test ; test performed with hormone measurements from the mother at the 15th-20th week of pregnancy
* Combined tests; It takes place with the sequential application of the above tests.The evaluation of these tests is carried out with a computer program.
* Genetic Ultrosonography; It is the examination of ultroson markers of genetic diseases by a competent practitioner during the 18th-23rd weeks of pregnancy. When a disease risk of 1/270 or more is detected from one or a combination of these tests, complete tests will be recommended by the physician.
Full Tests
* Chorionic villus sampling ( taking a sample from the baby’s placenta ) : it is performed during the 11th-14th week of pregnancy. it includes a 1-2% risk of miscarriage.
* Amniocentesis ( taking a sample from the baby’s water ) : it is performed during the 16th-20th week of pregnancy. the probability of pregnancy loss is reported to be up to 1%.
Cordosynthesis ( taking a sample from baby blood ) : Since it constitutes the most risky group of diagnostic tests, it should be preferred only in mandatory cases.
It is suggested that the family should learn about all the tests and decide whether to start taking the tests or not. If other complete tests are not performed when there is a high risk in a screening test, it may be difficult to get information from these test results during pregnancy. Again, when dawn syndrome is diagnosed early enough, termination of pregnancy by medical necessity is on the agenda. Families may have different decisions in this case as well.A method suitable for daily use has not yet been developed for the prevention of pregnancies affected by a complete test that will not have side effects on the baby and mother. In this regard, it is recommended that all pregnant families evaluate their condition with their physicians.
Updated Date : 28.02.2024
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